Brush holder construction for dynamo electric machines



July 30, 1963 T. GUTBERLET BRUSH HOLDER CONSTRUCTION FOR DYNAMO ELECTRICMACHINES Filed May 31. 1960 INVENTOR.

725000. 60 TBERLE'T United States Patent Oil-ice 3,099,761 Patented July30, 1963 3,09%,N1 BRUSH H'EBLDER CUNSTRUCTIGN FOR DYNAMU ELEQTRHQMAQHENES Theodor Gntherlet, Giessen, Germany, assignor to Schunir dzEire G.m.h.H., Giessen, Germany, a corporation of Germany Filed May 31,1960, Ser. No. 33,057 9 Claims. (Cl. 3102 l6) This invention relates toa brush construction for dynamo electric machines and is particularlyconcerned with an existing class of brush holders that can be improvedby eliminating the usual shunt connections that are ordinarily employedand by providing a structure that commutates directly with the brush,all without change in the basic design of the brush holder, it being ageneral object of this invention to avoid the deficiencies attend ant tothe use of shunt connections on brushes and that often become loosenedand ineffective.

Reference is made to applicants copending application Serial No. 849,790filed October 30, 1959, now Patent No. 3,049,037, entitled Brush Holdersfor Electrical Machinery.

The railroads, for instance, extensively use a brush holder of thegeneral type under consideration and wherein there is a thrust leverthat transmits force through an arcuate path to the brush, thedifference between that arcuate path and the rectilinear path of thebrush in the holder being compensated for by displacement of a thrustmember on the top plane of the brush. In twin brushes, as hereindisclosed, the thrust member rests in a recess in the top of the brushin order that the thrust may be applied to both pants of said brush. Thedifference then between thearcuate path of said thrust member and therectilinear path followed by the brush is usually compensated for byresiliently mounting a thrust finger in a thrust lever.

It is common practice in brush holders of this type to employ shunts, orpig-tails, from the brush per se to a terminal on the brush holder, andalthough this procedure and arrangement of parts has been used for manyyears there has always been the danger of these shunts coming loose. Asa result, the ordinary brush holders of this type are often damaged byarcing at improper points, resulting in untimely shut-down and repairsof the equipment involved.

Improvements are obtained by the present invention by use of a contactthat engages and biases the brush and which is connected to the brushholder by a shunt cable. The biasing mechanism, which is similar in somerespects to the mechanism disclosed in my above mentioned copendingapplication Serial No. 849,790, is characterized by pivoted andarticulated parts and it is imperative that electric-a1 current does notpass through the pivoted connections that are provided. Therefore, theprovision of the shunt cable becomes necessary together with insulationof said mechanism from the contact that engages the brush. As a result,the usual shunt that is necessary on ordinary brushes is eliminated andthe brushes become simple blocks of carbon, or the like, and they can bemore readily removed and replaced with considerably less eiiort, timeand expense.

It is an object of this invention to obviate the above mentioneddisadvantages by incorporating the shunt connection in the brush holderconstruction and eliminating it from the brush, thereby providing a veryreliable structure and greatly simplifying the brush construction. Withthe relationship of parts and elements as herein disclosed brushes canbe removed and/ or replaced with facility and expediency all to the endthat the invention is extremely useful and practical.

Another object of this invention is to provide a brush holder for dynamoelectric machinery and wherein there is little or no danger ofmalfunction of the parts involved, and especially no danger of theshunting of the brushes to become disconnected. With the structureherein disclosed the brushes are contacted mechanically and the shuntthat I provide protects the mechanism involved and so that there is nodanger of arcing at improper points.

It is still another object of this invention to provide a brush contactand biasing mechanism that can be used or employed in connection withexisting brush holder designs, all without change in said existing brushholders.

Further, it is an object of this invention to provide a very simple andinexpensive brush controlling mechanism and wherein the parts involvedare easy to make and reliable in their operation to bias the brush, tomake electrical contact therewith, and to damp undesirable vibrationsthat may otherwise occur.

The various objects and features of this invention will be fullyunderstood from the following detailed description of the preferred formand application thereof throughout which description reference is madeto the accompanying drawings, in which:

FIG. 1 is a side elevation of the brush holder of the present invention,showing it related to the periphery of a commutator and with portionbroken away to show in sect-ion.

FIG. 2 is a plan view taken as indicated by line 22 on FIG. 1 andillustrates the normal width of the device and the length of the brushengaged thereby.

FIG. 3 is a sectional view of a portion of structure of the presentinvention and taken as indicated by line 3-3 on FIG. 1.

The brush construction of the present invention is adapted for use,generally, in dynamoelectric machines, such as, for example, electricmotors and/ or generators, and in any like situation where commutationof electrical current is required. That is, the brush construction isadapted to be used in connection with commutators and sliprings to applypressure to a brush along its longitudinal axis and to conductelectrical current to and/or from the commutator and slip-rings. Asshown in the drawings, the invention involves, generally, a brush holder1 that slidably carries a brush 2, to guide it into engagement with acommutator 10, a thrust lever 4, a thrust finger 5 with a thrust member6 engageable with the brush 2, a vibration damping means 9 supportingthe thrust member 6 on the thrust lever 4, a link 8 pivoted relative tothe holder 1 and pivotally carrying the thrust lever 4, bias means 3 tourge the thrust lever and member into pressured engagement with thebrush 2, and a shunt cable 11 extending between the thrust finger 5 andthe brush holder 1.

The brush holder 1 is a frame-like part adapted to guide and direct thebrush 2 into engagement with the periphery of the commutator 10 and isof the usual construction and mounted on insulators at 15. Theperriphery of the commutator 10 is arcuate with the holder guiding thebrush 2 so that it projects radially of the commutator, the holder 1 andbrush 2 being of substantial length in order to allow for long wear ofsaid brush. In accordance with the invention, one side of the holder isopen or slotted at 2i in order to permit depressing of the brush 2 bythe thrust finger 5 and there is a lug 21 that is positioned laterallyof the slotted side of the holder, at the top side thereof andsubstantially spaced from the brush 2, to cooperatively carry and relatethe link 8 and thrust lever 4.

The brush 2, as shown throughout the drawings, is a twin brush ofcarbon, or the like, in that it involves a pair of like brush sections22 and 23. The drawings indicate the separate independent sections 22and 23, as they are guided by the holder 1 and accessible through theslotted answer opening at 20. In accordance with the invention, thesections 22 and 23 are arranged face to face in lateral engagement andthere is a notch 22' and 23' at the upper end of each section,respectively, said notches being arcuate and cooperatively forming asemi-circular seat or recess 7. Thus, the recess 7 is at the upper endof the brush 2 and adapted to receive the thrust member 6.

The link 8 is pivotally carried by the holder 1, being pivotallyconnected to the lug 21 by a pin 25 to project upwardly andsubstantially parallel with the brush 2. The pivotal axis of the link 8is removed laterally from the portion of the holder that carries thebrush and is disposed parallel with the commutator axis and parallelwith the adjacent side of the brush 2. In practice, the axis of the pin25 is at or near a plane substantially coincidental with and tangent tothe periphery of the commutator.

The thrust lever 4 is pivotally carried by the link 8 being pivotallyconnected to the upper and outer swinging end portion of the link 8 by apin 26 to project and swing toward the brush 2. The pivotal supportingaxis of the lever 4 is parallel with the above described pivotal axis ofthe link 8.

The thrust finger 5 is a continuation of and extends inwardly from theouter swinging end portion of the thrust lever 4 and is resilientlycoupled thereto by the vibration damping means 9. As shown, the lever 4and thrust finger 5 are coupled by an insulating structure thatcomprises a head 27 that carries the damping means 9 which comprises abody of rubber, or the like, that is resilient and electrically isolatesand yieldingly mounts the finger 5 on the outer end portion of the lever4. More particularly, the thrust finger 5 comprises a substantiallyflexible part that projects from the damping means 9 and carries thethrust member 6 to engage the top end of the brush 2. In accordance withthe invention, the thrust member 6 is carried at the terminal end of thefinger 5 and is a cylindrically-shaped part with its lower peripherysuitably coated or plated with conductive material and engaged in andseated in the recess 7, the member 6 and recess 7 being formed on acommon axis parallel with the axes of the above mentioned pins 25 and 26The head 27 is an inverted U-shaped part made of metal having,primarily, a transverse plate portion and in the preferred form it is apart separate from the lever 4 and has spaced depending side cheeks forconnection with the lever 4. Further, in the preferred form of theinvention, the lever 4 involves spaced parallel elements in which caseeach of said latter elements is engaged with and connected to a cheek ofthe head 27. In the drawings I have shown the lever elements joined tothe cheeks of the head by means of spaced pins 28 engaged therethrough,said cheeks being spaced by sleeves 29 surrounding the pins. In the caseillustrated the pins 28 are rivets that draw the parts into tightengagement, with the head :27 rigid with lever 4. The body of rubber, orthe like, that forms the damping means 9 surrounds the plane portion ofthe head 27 and the thrust finger 5 has a portion thereof wrapped aroundthe said rubber, or vibration damping body thereof, and clamped asclearly illustrated by the forwardmost rivet fastener, as shown.

The bias means 3 is preferably a spring bias means and involves a spring3d that is ltensioned and engaged with the outer end of the thrust lever4 in the form illustrated, the spring 30 is a clock-type spring carriedon a selectively rotatable bolt 32 securing the spring 30 to the holder1 and the spring 30 has a free and ac- .tive end that engages one of thepins 28 that couples the lever 4- to the head 27. In practice, the pins28 are positioned just below the plate portion of the head 27.

In accordance with the invention, I provide the shunt cable 11 thatextends between the thrust finger 5 and brush holder 1. The cable 11 isflexible in order to provide freedom of movement in the parts thus fardescribed and the cable ll serves to transmit current from the dthrustfinger 5 to the body of the holder 1 thereby avoiding transmission ofcurrent to the lever 4- and through the pins and 26. As shown, the cablell is a braided cable secured at its terminal ends to the finger 5 andholder 1, respectively.

The parts and elements, as above described, are related to each otherand operate as follows: The twin brush 2 guided in the brush holder 1 ispressed against the commutator ill by the tension spring acting by wayof the lever 4, thrust finger 5 and thrust member 6 which engages in therecess 7 in the brush top. The difference between the arcuate pathdescribed by the thrust member 6 and the rectilinear path described bythe brush 2 is compensated for between various positions by the link 3disposed between the lever 4 and the holder 1.

From the foregoing it will be apparent that the thrust lever is biasedby a spring pressure that is translated into thrust extendinglongitudinally of the brush. The usual difiicul-ty of shunted brushes isovercome in the holder according to the invention by the provision ofthe shunt cable ll which directly connects the brush to the holderthrough the cooperative relationship of the thrust member 6 thatcommutates with the brush 2 at the recess '7. This cooperativerelationship is furthered by the provision of conductive plating on thesurface of the said thrust member 6 and which is particularly adapted toconduct current to or from the twin brush 2. It will be apparent thatany electrical load is therefore carried through the thrust member 6,thrust finger 5 and cable ll, and under no circumstances is there anydanger of conduction through the mechanical parts involved in thebiasing mechanism, mainly the pin connections 25 and 26. Further, itwill be apparent that the damping means 9 electrically isolates thethrust finger 5 from the thrust lever 4, both electrically andmechanically. That is the thrust finger 5 and thrust lever 4- areseparated so that current does not flow therebetween and so thatmechanical vibrations are not carried from one part to the other.

I-lavmg described only the typical preferred form and application of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any variationsor modifications that may appear to those skilled in the :art and fallwithin the scope of the following claims.

Having described my invention, I claim:

1. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a thrust lever pivotally carried on the link and supporting an insulatedthrust member mechanically and electrically contacting the brush, biasmeans acting on the thrust lever and said member to move the brush as itwears, and the brush current being conducted by an electrical shuntextending from the thrust member.

2. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a thrust lever pivotally carried on the link and supporting an insulatedthrust member mechanically and electrically contacting the brush, biasmeans acting on the thrust lever and said member to move the brush as itwears, and the brush current being conducted by an electrical shuntextending between the thrust member and the holder.

3. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a thrust lever pivotally carried on the link and supporting an insulatedthrust member mechanically and electrically contacting the brush, biasmeans acting on the thrust lever and said member to move the brush as itwears, and the brush current being conducted by a flexible electricalshunt extending between the thrust member and the holder.

4. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a thrust lever pivotally carried on the link and extending toward thebrush, a thrust member supported by the thrust lever and mechanicallyand electrically contacting the brush as it wears, there beingelectrical insulation between the thrust lever and thrust member, biasmeans acting on the thrust lever to urge said thrust member intocontacting engagement with the brush, and the brush current beingconducted by an electrical shunt extending from the thrust member.

5. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a thrust lever pivotally carried on the link and extending toward thebrush, a thrust member supported by the thrust lever and mechanicallyand electrically contacting the brush as it wears, there beingelectrical insulation between the thrust lever and thrust member, biasmeans acting on the thrust lever to urge said thrust member into saidmechanical and electrical contacting engagement with the brush, and thebrush current being conducted by an electrical shunt extending betweenthe thrust member and the holder.

6. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a thrust lever pivotally carried on the link and extending toward thebrush, a thrust member supported by the thrust lever :and mechanicallyand electrically contacting the brush as it wears, there being a body ofresilient insulating material between the thrust lever and thrustmember, bias means acting on the thrust lever to urge said thrust memberinto said mechanical and electrical contacting engagement with thebrush, and the brush current being conducted by an electrical shuntextending from the thrust member.

7. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shifitably carry andguide the brush, a link pivoted on the holder laterally of the brush, athrust lever pivotally carried on the link and extending toward thebrush, a thrust member supported by the thrust lever and mechanicallyand electrically contacting the brush as it wears, there being a body ofresilient insulating material between the thrust lever and thrustmember, bias means acting on the thrust lever to urge said thrust memberinto said mechanical and electrical contacting engagement with thebrush, and the brush current being conducted by an electrical shuntextending between the thrust member and the holder.

8. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to shiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a pair of thrust levers pivotally carried on the link and extendingtoward the brush, a thrust member supported between the thrust leversand mechanically and electrically contacting the brush as it wears,there being electrical insulation between the thrust levers and thrustmember, bias means acting on the thrust levers to urge said thrustmember into said mechanical and electrical contacting engagement withthe brush, and the brush current being conducted by an electrical shuntextending from the thrust member.

9. A brush construction to urge a brush into engagement with acommutator and the like, and including, a holder to lshiftably carry andto guide the brush, a link pivoted on the holder laterally of the brush,a pair of thrust levers pivotally carried on the link and extendingtoward the brush, a thrust member supported between the thrust leversand mechanically and electrically contacting the brush as it wears,there being electrical insulation between the thrust levers and thrustmember, bias means acting on the thrust levers to urge said thrustmember into said mechanical and electrical contacting engagement withthe :brush, and the brush current being conducted by an electrical shuntextending between the thrust member and the holder.

References Cited in the file of this patent UNITED STATES PATENTS714,811 Litchfield Dec. 2, 1902 FOREIGN PATENTS 15,471 Great Britain of1912

1. A BRUSH CONSTRUCTION TO URGE A BRUSH INTO ENGAGEMENT WITH ACOMMUTATOR AND THE LIKE, AND INCLUDING, A HOLDER TO SHIFTABLY CARRY ANDTO GUIDE THE BRUSH, A LINK PIVOTED ON THE HOLDER LATERALLY OF THE BRUSH,A THRUST LEVER PIVOTALLY CARRIED ON THE LINK AND SUPPORTING AN INSULATEDTHRUST MEMBER MECHANICALLY AND ELECTRICALLY CONTACTING THE BRUSH, BIASMEANS ACTING ON THE THRUST LEVER AND SAID MEMBER TO MOVE THE BRUSH AS ITWEARS, AND THE